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One of the major characteristics of living organisms is metabolic rate — the amount of energy produced per unit of time. When the mass of organisms increases, the metabolic rate also increases (as a power function of mass), but usually slower than mass. This effect is called metabolic allometric scaling. Its causes are considered unknown. The effect has important implications for individual and population organismal development. It was shown in the first part of this study, presented in a separate paper, that in the case of multicellular organisms, this effect is a consequence of natural selection and optimization of nutrient distribution between the species of a food chain, sharing resources of a common habitat. Here, in the second part that studies unicellular organisms, we discover that the same principle of natural selection guided by optimization of nutrient distribution between the species of a food chain defines also metabolic allometric scaling of unicellular organisms. To find that, we consider the metabolic properties of Amoeba proteus, fission yeast Schizosaccharomyces pombe, Escherichia coli, Bacillus subtilis, Staphylococcus. The sharing of nutrients is optimized in such a way that bigger microorganisms have progressively bigger nutrient influx per unit of surface. This evolutionary arrangement secures the stability of a food chain by providing certain metabolic advantages for bigger organisms. Accounting for this regular increase of nutrient influx with mass increase, we obtained allometric exponents and their ranges close to experimental values, thus proving that metabolic allometric scaling of both multicellular and unicellular organisms is defined by the same fundamental evolutionary principle of optimized sharing of nutrients between the species of a food chain.

Magnetic nanoparticle plays an important role in biomedical engineering, especially in tumor therapy. In this paper, a new technique has been developed by using the rapid moving magnetic nanoparticle under a low-frequency alternating magnetic field (LFAMF) to kill tumor cells. The LFAMF system which was used to drive magnetic nanoparticles (MNPs) was setup with the magnetic field frequency and power range at ∼ 10–100 Hz and ∼ 10–200 mT, respectively. During the experiment, the LFAMF was adjusted at different frequencies and power levels. The experimental results show that the liver tumor cells (HepG2) mixed with MNPs (10 μg/mL) became partial fragments when exposed in the LFAMF with different frequencies (∼ 10–100 Hz) and power (∼ 10–200 mT), and the higher the frequency or the power, the more the tumor cells were killed at the same magnetic nanoparticle concentration. Conclusion: Tumor cells were effectively damaged by MNPs under LFAMF, which suggests that they had great potential to be applied in tumor therapy.